Sliding block puzzles are very old and even sliding block puzzles identical to the present puzzle are described in the August 1966 Canadian Patent 741696. That patent shows a puzzle with one large square object block, five rectangular blocks that are half the size of the target block, and four small square blocks that are one half the size of the rectangular blocks. All blocks are confined within a low-walled board that has inside dimensions equal to four small squares wide by five small squares in length. There is one empty space equal in size to a rectangular block so that various blocks may be moved on the board by moving into a vacant space. The large square object block is initially centered at one end of the board and the object is to maneuver it to the center of the opposite end where it may be removed through a fitted slot in the wall.
The same game with the same sliding blocks it described in 1990 U.S. Pat. No. 4,927,150. But here all blocks except the large square object block are keyed into slots in the board floor and are not removable. However, breaks in the walls of the board enable the object block to be removed from its target position and reinserted into its initial position at the opposite end of the board.
The slidable block puzzle to be described is played in a hinged square box having a cover or lid and a smooth playing board, both lid and playing board with solid low walls. The interior surface of the lid is partitioned to accommodate each block in its initial playing position. The space between the interior surfaces of the lid and the playing board is very little more than the thickness of the blocks so that when the lid is closed with the blocks within their partitions, the blocks remain captured in the partitions and there is a minimum of rattling of the blocks. When inverted and the lid is opened the blocks are in their initial position on the smooth surface of he playing board for maneuvering the large square object block to its target position in the center of the opposite end.